This circuit uses a transistor as a sensor and operates in the range of 0 to 50º C. We found it in old documentation. Operational equivalents can be used.
This circuit appears in several versions in publications of the time and can be modified by...
This configuration with FET and Unijunction can be found elsewhere on this site. The JFET admits...
We found this circuit in a Popular Electronics from the 90s. It operates at a frequency of 15 kHz....